Study of dielectric characteristics of graded Ba1-xCaxZr0.05Ti0.95O3 thin films grown by a sol-gel process

The compositionally graded Ba1-xCaxZr0.05Ti0.95O3 (x = 0, 0.05, 0.10) (BCZT) thin films with compositional gradient from BaZr0.05Ti0.95O3 to Ba0.90Ca0.10Zr0.05Ti0.95O3 were deposited on Pt/Ti/SiO2/Si substrates by sol-gel processing. The crystal structure of the thin films was determined by X-ray diffraction. Field emission scanning electron microscopy (FESEM) was used to examine crystallite size and morphology of compositionally graded thin films. The dielectric properties of compositionally graded thin films were characterized by measuring the dielectric constant and dielectric loss as a function of temperature, applied electric field and frequency. As a result, compositionally graded thin films with weak temperature dependence were realized. Dielectric constant peaks, common to a ferroelectric transition, were not observed in the temperature range from 298 to 413 K. The compositionally graded BCZT thin films with weak temperature dependence of tunability could be attractive materials for frequency and phase agile tunable microwave components such as tunable filters, tunable oscillators, and phase shifters for application in phased array antennas.